Method for producing conjugated diolefin

Abstract

A method for producing a conjugated diolefin is configured as follows. A monoolefin having four or more carbon atoms is fed from a monoolefin feed nozzle(s) installed at n place(s) (n=1, 2, . . . , n). In addition, at least 50% or more of a total amount of an oxygen-containing gas is fed from an oxygen-containing gas feed nozzle located at a bottom of a fluidized bed reactor. Furthermore, the monoolefin feed nozzles at heights a1, a2, . . . , an from the oxygen-containing gas feed nozzle feed the monoolefin having four or more carbon atoms at ratios of b1, b2, . . . , bn (b1+b2+ . . . +bn=1), respectively, and a weighted mean value represented by the following formula and obtained from the above heights and the above ratios is 200 mm to 3000 mm. arithmetic mean value= a 1* b 1+ a 2* b 2+ . . . + an*bn

The invention claimed is: 
     
       1. A method for producing a conjugated diolefin, the method comprising:
 feeding a monoolefin having four or more carbon atoms and an oxygen-containing gas into a fluidized bed reactor having an oxide catalyst containing molybdenum thereinside, and bringing the oxide catalyst, the monoolefin having four or more carbon atoms, and the oxygen-containing gas into contact with each other to produce a conjugated diolefin, 
 wherein the monoolefin having four or more carbon atoms is fed from a monoolefin feed nozzle(s) installed at n place(s) (n=1, 2, . . . , n), 
 at least 50% or more of a total amount of the oxygen-containing gas is fed from an oxygen-containing gas feed nozzle located at a bottom of the fluidized bed reactor, 
 the monoolefin feed nozzles at heights a1, a2, . . . , an from the oxygen-containing gas feed nozzle feed the monoolefin having four or more carbon atoms at ratios of b1, b2, . . . , bn (b1+b2+ . . . +bn=1), respectively, and 
 an weighted means value represented by a following formula and obtained from the heights and the ratios is 200 mm or more and 3000 mm or less:
   weighted means value= a 1* b 1+ a 2* b 2 + . . . +an*bn.    
 
 
     
     
       2. The method for producing a conjugated diolefin according to  claim 1 , wherein a number of the monoolefin feed nozzles per unit area is 10/m 2  or more. 
     
     
       3. The method for producing a conjugated diolefin according to  claim 1 , wherein a network structure having an opening ratio of 60% or more is disposed above a position of the monoolefin feed nozzle. 
     
     
       4. The method for producing a conjugated diolefin according to  claim 3 , wherein feed of the monoolefin having four or more carbon atoms is performed at one stage. 
     
     
       5. The method for producing a conjugated diolefin according to  claim 1 , wherein feed of the monoolefin having four or more carbon atoms is performed at one stage. 
     
     
       6. The method for producing a conjugated diolefin according to  claim 1 , wherein the monoolefin having four or more carbon atoms is n-butene or isopentene. 
     
     
       7. The method for producing a conjugated diolefin according to  claim 6 , wherein the oxide is represented by the following empirical formula, and the support is one or more selected from the group consisting of silica, alumina, titania, and zirconia,
   Mo 12 Bi p Fe q A a B b C c D d E e O x    
 wherein A is at least one element selected from nickel and cobalt, B is at least one element selected from alkali metal elements, C is at least one element selected from magnesium, calcium, strontium, barium, zinc, and manganese, D is at least one rare earth element, E is at least one element selected from chromium, indium, and gallium, O is oxygen, p, q, a, b, c, d, e, and x represent atomic ratios of bismuth, iron, A, B, C, D, E, and oxygen to 12 molybdenum atoms, respectively, respectively, 0.1≤p≤5, 0.5≤q≤8, 0≤a≤10, 0.02≤b≤2, 0≤c≤5, 0≤d≤5, and 0≤e≤5 are satisfied, and x is a number of atoms of oxygen required to satisfy valence requirements of other elements present. 
 
     
     
       8. The method for producing a conjugated diolefin according to  claim 7 , wherein the monoolefin having four or more carbon atoms, and at least one gas selected from the group consisting of nitrogen, water vapor, and carbon dioxide are fed from the monoolefin feed nozzle. 
     
     
       9. The method for producing a conjugated diolefin according to  claim 1 , wherein an oxygen concentration of a reactor outlet gas is 0.2% by volume or more and 2.0% by volume or less.